A convenient synthesis of substituted pyrazolidines and azaproline derivatives through highly regio- and diastereoselective reduction of 2-pyrazolines

作者：Santos Jesus M De los; Lopez Yago; Aparicio Domitila; Palacios Francisco^*

来源：Journal of Organic Chemistry, 2008, 73(2): 550-557.

DOI：10.1021/jo702050t

The synthesis of substituted N-acetyl- and N-aroyl-2-pyrazolines via intramolecular Michael addition of alpha,beta-unsaturated hydrazones generated through olefination of phosphinyl and phosphonyl hydrazones with carbonyl compounds is reported. The regioselective reduction of the C-N double bond in these 2-pyrazolines using Superhydride (Et3BHLi) gives pirazolidine derivatives with excellent levels of cis-diastereoselectivity. These 2-pyrazolines can also be obtained in one-pot reaction from allenes, hydrazides, and aldehydes; and pyrazolidines, after reduction, from allenes, hydrazides, and aldehydes. This synthetic route was developed to provide a new approach to substituted azaproline derivatives in a diastereoselective fashion.

• 出版日期2008-1-18